Spring operated fire alarm

ABSTRACT

A siren transducer is mounted in a louvered enclosure. A spiral spring energizes the transducer through a step-up gear train when a thermally responsive gear brake is moved to a release position which occurs when a predetermined temperature is exceeded.

United States Patent Ha] E. Cushman P.O. Box 25, Ronald, Wash. 98940; Robert W. Bell, Jr., Roslyn, Wash. 806,410

Mar. 12, 1969 Feb. 2, 1971 Said Bell assignor to said Cushman Inventors Appl. No. Filed Patented Assignee SPRING OPERATED FIRE ALARM 3 Claims, 3 Drawing Figs.

US. Cl. 116/102 Int. Cl. G08b 17/00 l 16/ 102,

FieldofSearch References Cited UNITED STATES PATENTS Stevens Oberreich Ormsby Osborn Birtciel Miller et al. Johnston Palmer Sfreddo Fink Primary Examiner-Louis J. Capozi Attorneys-Clarence A. OBrien and Harvey B. Jacobson ABSTRACT: A siren transducer is mounted in a louvered enclosure. A spiral spring energizes the transducer through a step-up gear train when a thermally responsive gear brake is moved to a release position which occurs when a predetermined temperature is exceeded.

SPRING OPERATED FIRE ALARM The present invention relates to fire alarm devices and more particularly to a self-contained portable and hand-wound alarm.

In the past. small portable fire alarms have been provided which issue an alarm signal in response to excessive temperature, indicative of fire in the vicinity. Most portable alarm devices of this type includes a miniature electric motor for driving the siren transducer. Motor power is provided by batteries which provide a constant source of device unreliability due to weakened or discharged batteries incapable of issuing an alarm signal. In order to insure reliable operation of such electrical alarm devices, the batteries must be frequently checked and replaced as needed. This is inconvenient and requires continual financial expenditure.

The present invention includes a siren transducer actuated by a hand-wound spiral spring through an intermediary step up gear train. The present invention may be conveniently utilized in campers, trailer homes, tents, hotel and motel rooms, offices, and residential homes. Because the invention is powered by a key wound spiral spring, there is no reliance upon electrical power from a source which might fail, be it from a wall outlet or from batteries. The invention further includes means for adjusting the threshold or triggering level that makes the alarm device operative. This means, that the alarm may be adjusted to respond to a variable preselected temperature.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIG. 1 is a perspective view of the exterior fire alarm housmg.

FIG. 2 is a vertical cross-sectional view taken along a plane passing through section line 22 of FIG. 1 illustrating the interior components of the alarm.

FIG. 3 is a transverse sectional view taken along a plane passing through section line 3-3 of FIG. 2.

Referring to the drawings and more particularly FIG. 1 thereof, the present portable and self-contained fire alarm is generally indicated by reference numeral and includes a base plate 12 shown in FIG. 2 to which a boxlike cover 14 is removably fastened by suitable screw fasteners 18. The boxlike cover includes louvers 16 therein to permit thermal and accoustic communication between the interior of the alarm device and the atmosphere.

Referring to FIG. 2-, a bushing 20 is received within the base plate 12, the outward end of the bushing extending to a recess 22 is formed inwardly of the rearward base plate surface. A shaft 24 passes through the bushing 20 and extends to the interior of the housing 14. A spiral spring 26 has its interior convolution keyed to the shaft 24 at the interior end thereof. The end of the outer convolution 28 is secured by means of a pin or the like to a radially outward point of a first gear wheel 34 freely mounted on shaft 24 between the inward surface of the base plate 12 and the spiral spring 26. In order to permit the spiral spring 26 to be wound, a conventional pawl 30 is pivotally mounted to the base plate 12 and is positioned to engage a ratchet 32 keyed to the shaft 24 at a position adjacent the inward surface 25 of the base plate 12. A pivotally con- 1 nected winding key 33 is mounted to the outward end of shaft 24 and is normally received in a flat position within recess 22. When winding of the spiral key 26 is required, the key 33 is pivoted upwardly thereby permitting winding of the shaft 24 and the spiral spring 26 connected thereto.

In operation of the device, after the spiral spring 26 is fully wound, the pawl and ratchet 30 and 32 respectively prevent the unwinding of the spiral spring until a preselected thermal condition occurs as hereinafter explained.

The present invention includes a siren transducer 35 which requires rapid rotation of an associated input shaft as hereinafter explained. Suffice to say at this point that the present alarm device includes a gear train to transmit rotational motion from gear wheel 34 to the transducer shaft at an increased angular velocity.

The mentioned gear train includes a second gear wheel 40 which is diametrically smaller than the gear wheel 34 and performs a velocity step-up function. The gear wheel 40 is mounted to a shaft 38 which is received within a bushing 36, the latter being recessed within the base plate 12. A third gear wheel 42 is mounted in axial spaced relation to the second gear wheel 40 and does not engage the prior mentioned gear wheels 34 or 40. Rather, the third gear wheel 42 is adapted to mesh with a fourth gear wheel 44 mounted to a shaft 46, disposed in parallel relation to the aforementioned shafts 38 and 24. The shaft 46 rotates within the bushing 48 received within the base plate 12. The gear wheel 44 is of smaller diameter than the meshing gear wheel 42 so that gear wheel 44 performs a velocity step-up function.

A fifth gear wheel 50 of larger diameter than the gear wheel 44 is keyed to shaft 46 in axial spaced relation with respect to the fourth gear wheel 44. As will be noted from the FIG., the latter mentioned gear wheel 50 does not mesh with any of the gear wheels of the previously described gear train portion. Instead, this gear wheel meshes with a sixthgear wheel 52 which is of smaller diameter than the fifth gear wheel 50 thereby effecting an additional velocity step of function. The sixth gear wheel 52 is keyed to shaft 54 which extends rearwardly into a bushing 56 received in vase plate 12.

It is the latter mentioned shaft 54 which drives the conventional siren transducer 35. In operation of the device, once the spiral spring 26 is wound, it stores potential energy until a preselected ambient thermal condition triggers the alarm so that the potential energy of the spiral spring may be transformed to kinetic energy for driving the gear train which in turn actuates the siren transducer 35.

In order to better appreciate the triggering mechanism, reference is continued to FIG. 2 which illustrates the thermally responsive brake generally indicated by 62 which includes a bimetallic strip 66 connected in cantilevered fashion to a mounting block 64, which in turn is attached to the base plate 12 by suitable fasteners 68. The free end of the bimetallic strip 66 is shaped in the form of a pawl as indicated by reference numeral 74. A ratchet wheel 58 is keyed to the alarm transducer shaft 54 in axial spaced relation between the sixth gear wheel 52 and the transducer.

Thus, as the key 33 is rotated, the spiral spring 26 is wound. The pawl action of the bimetallic strip 66 engaging the ratchet wheel 58, prevents all gears in the gear train from rotating. However, when a preselected thermal condition occurs, the bimetallic strip 66 moves to a disengaged position as indicated in phantom by reference numeral 76. This frees the gear train from further braking action and causes the outer convolution end 28 of the wound spiral spring 26 to rotate the first gear wheel 34 which in turn causes stepped up operation of the entire aforementioned gear train. This gear train operation will cause the alarm transducer to issue an alarm signal.

In order to set the preselected thermal condition which triggers the alarm, an adjusting screw 70 is provided which has an inward end bearing against an intermediate section of the bimetallic strip. The bolt extends at an opposite end thereof through the box cover 14 so adjustment of the screw may be effected from the outside. The screw is threadedly engaged with a support nut 72 suitably attached to the inner surface of the housing cover 14. The outwardly exposed end of the screw 70 includes a knurled knob with gradations thereon which roughly correspond to temperature. Viewing FIG. 2 it will be noted that the inward end of the screw 70 bears against the flexing body of the bimetallic strip 66 so that by adjusting the screw 70, the degree of engagement between the bimetallic strip 66 and the ratchet wheel 58 may be varied. For example, if the engagement is lessened, a smaller increase in ambient temperature will trigger the alarm into operation. Accordingly, the user may adjust the alarm to be triggered at a temperature which he considers to be indicative of an abnormal thermal condition indicating the presence of nearby fire.

The present device may be conveniently mounted to a nearby wall or other structure by means of an eye fastener 48 suitably attached to the upwardly disposed transverse end of 5 the housing cover 14. A hook fastener 80 received within the vertical supporting surface 82 provides the removable mounting of the alarm device.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

We claim:

1. A fire alarm device enclosed within a housing, the device comprising an alarm transducer, driving means for powering the device, force transmitting means connecting the driving means to the transducer, a substantially straight bimetallic element serving as a brake for the force transmitting means. means connected to the housing for supporting the element in a cantilevered manner, the free end of the element normally engaging the force transmitting means, the element responsive to a preselected temperature for causing element movement from the engaged position which permits free operation of the force-transmitting means and in turn causes actuation of the alarm transducer.

2. A fire alarm device enclosed within a housing. the device comprising an alarm transducer, a key wound spiral spring, gear means connected between the spring and the transducer, a substantially straight bimetallic element serving as a brake for the gear means and restraining operation thereof, means connected to the housing for supporting the element in a cantilevered manner, the free end of the element normally engaging the gear means, the bimetallic element being responsive to a preselected temperature for causing element movement from the engaged position thereby permitting free operation of the gear means and the connected alarm transducer.

3. The device set forth in claim 2 together with adjustment means for varying the degree of engagement between the element and the gear means thereby effecting an adjustable alarm-triggering condition, the adjustment means comprising a threaded member mounted in the housing, the member including a head disposed outwardly of the housing for making an adjustment, the member extending inwardly to a free end which contacts an intermediate point of the element and displaced the element as the head is turned. 

1. A fire alarm device enclosed within a housing, the device comprising an alarm transducer, driving means for powering the device, force transmitting means connecting the driving means to the transducer, a substantially straight bimetallic element serving as a brake for the force transmitting means, means connected to the housing for supporting the element in a cantilevered manner, the free end of the element normally engaging the force transmitting means, the element responsive to a preselected temperature for causing element movement from the engaged position which permits free operation of the forcetransmitting means and in turn causes actuation of the alarm transducer.
 2. A fire alarm device enclosed within a housing, the device comprising an alarm transducer, a key wound spiral spring, gear means connected between the spring and the transducer, a substantially straight bimetallic element serving as a brake for the gear means and restraining operation thereof, means connected to the housing for supporting the element in a cantilevered manner, the free end of the element normally engaging the gear means, the bimetallic element being responsive to a preselected temperature for causing element movement from the engaged position thereby permitting free operation of the gear means and the connected alarm transducer.
 3. The device set forth in claim 2 together with adjustment means for varying the degree of engagement between the element and the gear means thereby effecting an adjustable alarm-triggering condition, the adjustment means comprising a threaded member mounted in the housing, the member including a head disposed outwardly of The housing for making an adjustment, the member extending inwardly to a free end which contacts an intermediate point of the element and displaced the element as the head is turned. 